Repair / Help Forum > Repair / Help

Marantz PM7200 Can't adjust Bias or DC Offset

<< < (2/2)

mossieurclo:
igottheshieldsoff igottheshieldsoff igottheshieldsoff igottheshieldsoff

! ;0 GOT  THE ;O SHIELDS ;D OFF ;"!!!!!!!  ;D ;D ;D ;D



:banana::jump::banana:

mossieurclo:

--- Quote from: mossieurclo on October 04, 2020, 11:47:51 PM ---I ordered a mega328 esr meter, and a solder sucker. 1 week?

So i plan to annotate a .pdf with my readings and post it, hoping someone more experienced than i will be there to read it and advise. :scared:

--- End quote ---

I got the meter and solder pump today.

I calibrated the meter, rigged pins and alligators to extend the ZIF socket, tested a few cans in my NOS and 7267 of the Marantz that i had taken out (it's good :-().

That puny meter looks useful.  :police: ;D

For Google customers searching, a pretty good manual (not supplied with the lower priced item from Amazon.ca) for "LCR-T4 Mega328 Component Tester" is here:

https://kookye.com/download/manual/mega328_transistor_tester_user_guide-...

Now brace yourselves, friends. Data storm coming soon. Thanks for weathering it.

(i should not play with those words, sorry for those who live through those very real weather storms down south)

mossieurclo:

--- Quote from: mossieurclo, post: 14153049, member: 330919 ---After i repaired the speaker protection board of that amplifier, all was ok.

So I then proceeded to adjust iddle current, got it, then DC offset. Oh, bboy.
[...]
--- End quote ---

Summing up how that problem was resolved (thank you to all who contributed!!):

I replaced fusible resistor 3315 that had gone very high.

And lowered 3301 (and 3302) to 220R to bring DC back within adjustable range (7267 and 7268 having drifted?)

Now will be replacing lots of electrolytics, all other fusibles, and putting back 7289 that i blew up (remember: discharge those Caps!), to reenable Protection. Looking for that 2SA970 and other through hole legged critters i discovered that these are now really scarce, like in hard to find.

Are NTE replacements viable??

Vpgh:

--- Quote from: mossieurclo on November 06, 2020, 11:40:17 AM ---
--- Quote from: mossieurclo, post: 14153049, member: 330919 ---After i repaired the speaker protection board of that amplifier, all was ok.

So I then proceeded to adjust iddle current, got it, then DC offset. Oh, bboy.
[...]
--- End quote ---
. Looking for that 2SA970 and other through hole legged critters i discovered that these are now really scarce, like in hard to find.

Are NTE replacements viable??

--- End quote ---
I believe that I have a couple on my bench. Please PM me

mossieurclo:
Thank you! PM sent.

Navigation

[0] Message Index

[*] Previous page